As a standard user, you may flag an inappropriate comment in any forum by clicking on the flame icon next to the comment:

Administrators may choose to delete or accept messages flagged as inappropriate. 

To minimize the possibility of unruly behavior, administrators may choose to ensure that discussion forums are moderated (I.e., all messages require administrative approval before they are posted) or limited to certain groups (i.e., they are not open to members of the public, only groups that have been defined in SeaSketch).